MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 28W (DAMREY) WARNING NR 09// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON 28W (DAMREY), LOCATED APPROXIMATELY 222 NM SOUTHEAST OF DA NANG, VIETNAM, HAS TRACKED WESTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS A SYMMETRIC SYSTEM WITH DEEP CONVECTION. A 031800Z HIMAWARI INFRARED SATELLITE IMAGE SHOWS A NOTCH FEATURE ASSOCIATED WITH THE LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL INTENSITY OF 90 KNOTS IS BASED ON DVORAK INTENSITY ESTIMATES OF T5.0 (90 KNOTS) FROM BOTH PGTW AND KNES. ENVIRONMENTAL ANALYSIS INDICATES THE SYSTEM IS IN A FAVORABLE AREA, WITH LOW TO MODERATE (5-15 KNOTS) VERTICAL WIND SHEAR (VWS) AND IS TRACKING THROUGH AN AREA OF WARM (27-28 CELSIUS) SEA SURFACE TEMPERATURES. THE SYSTEM HAS GOOD EQUATORWARD OUTFLOW AND A VERY STRONG POLEWARD OUTFLOW CHANNEL THAT IS CURRENTLY BEING ENHANCED BY THE MID-LATITUDE WESTERLIES LOCATED OVER SOUTHERN CHINA. TY 28W IS TRACKING WESTWARD ALONG THE SOUTHERN BOUNDARY OF THE SUBTROPICAL RIDGE (STR) LOCATED TO THE NORTH. 3. FORECAST REASONING. A. THERE IS NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 28W WILL CONTINUE TO TRACK WESTWARD ALONG THE SOUTHERN EXTENT OF THE STR FOR THE DURATION OF THE FORECAST. TY DAMREY WILL CONTINUE TO INTERACT WITH COASTAL VIETNAM AND WILL WEAKEN IN INTENSITY WITH ADDITIONAL LAND INTERACTION. TY 28W WILL MAKE LANDFALL OVER SOUTH-CENTRAL VIETNAM AROUND TAU 6. AFTER LANDFALL, THE RUGGED TERRAIN OF THE INDO-CHINA PENINSULA WILL RAPIDLY WEAKEN THE SYSTEM AS IT TRACKS WESTWARD. TY DAMREY WILL DISSIPATE BY TAU 36. AVAILABLE DYNAMIC MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH THE FORECAST PERIOD, LENDING HIGH CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN NNNN